package org.shuker.executor.impl;

import org.shuker.pojo.Configuration;
import org.shuker.pojo.MappedStatement;
import org.shuker.executor.BoundSql;
import org.shuker.executor.Executor;
import org.shuker.utils.GenericTokenParse;
import org.shuker.utils.ParameterMapping;
import org.shuker.utils.ParameterMappingTokenHandler;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

/**
 * @author ：Shuker
 * @date ：Created in 2022/6/14 11:38
 * @description：
 * @version:
 */
public class SimpleExecutor implements Executor {
    private Connection connection = null;

    @Override
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object[] param) throws Exception {
//        获取连接
        connection = configuration.getDataSource().getConnection();
//        select * from user where id = #{id} and username = #{username}
        String sql = mappedStatement.getSql();
//        对sql进行处理
        BoundSql boundSql = getBoundSql(sql);
//        获取预处理对象
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());
//        设置参数
//        获取到了参数的全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass = getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();
//            反射
            Field declaredField = parameterTypeClass.getDeclaredField(content);
//            暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(param[0]);
            preparedStatement.setObject(i + 1, o);
        }
//        执行sql
        ResultSet resultSet = preparedStatement.executeQuery();
        String resultType = mappedStatement.getResultType();
        Class<?> resultClassType = getClassType(resultType);
        ArrayList<Object> objects = new ArrayList<>();
//        封装返回结果集
        while (resultSet.next()) {
            Object o = resultClassType.newInstance();
//            元数据
            ResultSetMetaData metaData = resultSet.getMetaData();
            for (int i = 1; i <= metaData.getColumnCount(); i++) {
//                字段名
                String columnName = metaData.getColumnName(i);
//                字段值
                Object value = resultSet.getObject(columnName);
//                使用反射或者内省，根据数据库表和实体的对应关系，完成封装
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, resultClassType);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o, value);
            }
            objects.add(o);
        }
        return (List<E>) objects;
    }

    @Override
    public int update(Configuration configuration, MappedStatement mappedStatement, Object[] param) throws Exception {
//        获取连接
        connection = configuration.getDataSource().getConnection();
//        获取SQL
        String sql = mappedStatement.getSql();
//        对SQL进行处理
        BoundSql boundSql = getBoundSql(sql);
//        获取预处理对象
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());
//        设置参数
//        获取参数的全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass = getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();
//            反射
            Field declaredField = parameterTypeClass.getDeclaredField(content);
//            暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(param[0]);
            preparedStatement.setObject(i + 1, o);
        }
//        执行SQL
        int i = preparedStatement.executeUpdate();
        return i;
    }


    private Class<?> getClassType(String parameterType) throws ClassNotFoundException {
        if (parameterType != null) {
            Class<?> aClass = Class.forName(parameterType);
            return aClass;
        }
        return null;
    }

    @Override
    public void close() throws SQLException {
        connection.close();
    }

    private BoundSql getBoundSql(String sql) {
//        标记处理类：配置标记解析器来完成对占位符的解析处理工作
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParse genericTokenParse = new GenericTokenParse("#{", "}", parameterMappingTokenHandler);
//        解析出来的sql
        String parseSql = genericTokenParse.parse(sql);
//        #{}里面解析出来的参数名称
        List<ParameterMapping> parameterMappingList = parameterMappingTokenHandler.getParameterMappingList();
        BoundSql boundSql = new BoundSql(parseSql, parameterMappingList);
        return boundSql;
    }
}
